Preliminary investigations of isotope effects in the dopamine-Beta-hydroxylase catalyzed oxidation of tritiated dopamine indicate a wide range of isotope effects, depending on the oxygen and fumarate concentrations. Stereospecifically deuterated dopamines have been synthesized, and will be used in a rigorous study of isotope effects in this system. Structure reactivity correlations and isotope effects in the redution of benzaldehydes catalyzed by benzyl alcohol dehydrogenase from Pseudomonas putida, suggest a transition state structure similar to that observed for the reactions catalyzed by yeast and horse liver alcohol dehydrogenase. Substituent and isotope effects in the bacterial alcohol dehydrogenase catalyzed oxidation of benzyl alcohol will be investigated in an effort to confirm the proposed transition state structure.